setup: move the certificate generation

Generating the certificate at the service startup (instead of during the
rpm installation) has a better chance to succeed (and a better recovery
process). Moreover this allows appliances (like ovirt-node) to postpone
the certificate generation when the service is actually used for the
first time.

In this patch:
* Move the certificate generation from the spec file to the init file

Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=860067
Signed-off-by: Federico Simoncelli <fsimonce@redhat.com>
Change-Id: I40fa3d9a6a54e312e399af3f87ac67e843078360
Reviewed-on: http://gerrit.ovirt.org/8368
Reviewed-by: Dan Kenigsberg <danken@redhat.com>
Reviewed-by: Michael Burns <mburns@redhat.com>
Tested-by: Michael Burns <mburns@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/10615